Conventionally known is, in order to prevent electronic components from degrading caused by heat emitted by the electronic components, an information processor including a plurality of cooling fans for cooling the electronic components.
The cooling fan of such an information processor emits a sound rich in a specific frequency component in accordance with its rotation speed. Given this situation, when setting the rotation speeds of the respective cooling fans of the information processor to be the same rotation speed, the information processor increases the sound level of the specific frequency component and produces noise.
Known is an information processor that sets the rotation speeds of the cooling fans to be different rotation speeds in order to reduce such kind of noise or the like. Such an information processor sets the rotation speeds of the respective cooling fans of the information processor to be different rotation speeds, thereby displacing the peaks of the frequency components of the sounds emitted by the respective cooling fans and reducing noise.
Patent Document 1: Japanese Laid-open Patent Publication No. 2000-242340
Patent Document 2: Japanese Laid-open Patent Publication No. 06-117743
Patent Document 3: Japanese Laid-open Patent Publication No. 2002-023267
However, the technology that sets the rotation speeds of the cooling fans of the information processor to be different rotation speeds cannot reduce noise appropriately when a plurality of information processors are operated at the same time.
For example, it is hard to predict in advance noise emitted by the entire information processing system that includes a plurality of information processors in which information processors of different makers coexist. Because of this, unless the information processing system is actually operated, the noise emitted by the information processing system cannot be confirmed. As a result of this, the above technology cannot perform feedback control based on the noise emitted by the information processing system on the setting of the rotation speeds of the cooling fans of the respective information processors. The above technology cannot predict in advance noises emitted by the respective information processors and noise emitted by part of the information processors through a specific frequency component that is emphasized, unless the information processing system is actually operated.
Although in a computer room in which an information processing system is installed such as a data center noise is less problematic, a specific frequency component may propagate to the surroundings of the computer room and produce noise depending on the structure of a building in which the information processor is installed. It is hard to predict noise emitted by such an information processing system before the information processing system is installed.